The present invention relates generally to conduits for conveying fluids, and particularly to a flexible conduit assembly for conveying a pressurized fluid.
Various automotive and industrial fluids, such as water, fuel, hydraulic and engine oil, and refrigerant, for example, are typically conveyed from one component to another. Frequently such fluids must be conveyed under somewhat severe flow parameters or environmental conditions, such as high pressures, widely varying fluid and ambient temperatures, dirt, dust and vibration. Additionally, space is usually at a premium in such automotive and industrial applications, and the pipe or conduit conveying the fluid is often required to follow a tortuous path with several bends of different angles along its length. Further adding to the complexity of such installations, the size, weight and cost of the pipe or conduit should be minimized, while its reliability is maximized. Accordingly, it is a principal object of the present invention to provide a high-strength flexible conduit or piping structure which will both satisfy the above requirements and yet be economical and simple to manufacture and install.
In accordance with the present invention, a tubular conduit assembly for conveying a pressurized fluid preferably includes a flexible, thin-walled plastic inner tube disposed coaxially within a generally coextensive flexible outer tube which functions as a high-strength armor structure for the assembly. The thin-walled plastic inner tube preferably includes one or more helically-extending corrugations to further enhance its flexibility, and the flexible outer tube or armor is preferably constructed from at least one helically-wound, high-strength member. The helical corrugations of the inner tube and the helically-wound member or members of the outer tube or armor have a corresponding, generally coextensive configuration and engage one another in a manner similar to the threadable engagement of bolt within a nut. The flexible inner tube, is preferably a thermoplastic or other material suitable for the conditions and chemistry of the fluid being confined and conveyed, and is sufficiently flexible and thin-walled to be deformed by the pressure and/or temperature of the fluid in order to form a sealing layer or coating on the interior of the outer tube.
In the preferred embodiment, the outer tube is constructed of a high-strength, helically-wound member having two or more generally oppositely-presenting channel-shaped, portions which are interlaced in a slidably interlocking configuration. Since the generally channel-shaped portions have opposite presentations, each of the channel-shaped portions has one of its legs slidably interposed between the legs of the adjacent channel-shaped portion in order to provide the interlocking, but flexible, structure. Thus, when the flexible inner tube deforms in response to the pressure and/or temperature of the fluids being conveyed, it provides a fluid-tight internal layer or sleeve which internally seals the helically-wound member or members of the outer tube without sacrificing the flexibility thereof.
The preferred tubular conduit assembly also includes an annular portion located adjacent an end of the flexible inner tube adapted to be connected to a fluid containing component. Such a fluid-containing component may have a nipple member, for example, which is insertable into an open end of the conduit assembly. In such an arrangement, a shrink fitting is provided for compressingly urging the annular portion of the inner tube into a sealing relationship with the nipple member and also for anchoring the flexible outer tube with respect to the nipple member. The shrink fitting preferably includes an external collar threadably and coaxially disposed around the helically-wound channel-shaped member or members of the outer tube. As the collar is threaded into a circumscribing relationship with the outer and inner tubes and the nipple member, the annular portion on the end of the inner tube is sealingly compressed. The annular portion may also be generally channel-shaped and include a sealing member therein.
Additional objects, advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.